This invention relates to a car power source apparatus provided with a heater to increase the temperature of the driving battery that powers the electric drive motor of a vehicle, such as an automobile, when temperatures are low.
When temperatures become extremely low, battery output decreases and sufficient performance cannot be obtained. Consequently, when a hybrid car is used in a location of extreme cold and the temperature of the driving battery becomes low, battery performance is not sufficient to start the car. A hybrid car is designed to normally run on both an engine and an electric motor. If performance of the driving battery decreases and power from the motor is insufficient, the hybrid car cannot operate normally. This drawback can be resolved by warming-up (heating) the battery. To realize this, the present applicant developed a power source apparatus which warms-up rechargeable batteries via a heater (refer to Japanese Patent Application Disclosure 2003-223938).
The power source apparatus disclosed in this patent reference is provided with a driving battery comprising a plurality of rechargeable batteries, and a heating plate, with a heater mounted on it, to warm-up (heat) the rechargeable batteries of the driving battery. The heating plate is disposed in close proximity to the rechargeable batteries to allow efficient heating of those rechargeable batteries. Electric current is passed through the heating plate heater of this power source apparatus to heat the heater via Joule heating. Many heaters are disposed in close proximity to many rechargeable batteries to heat those batteries.
A power source apparatus, which warms-up (heats) the driving battery when the car is started in an extremely cold climate location, where outside air temperature drops, for example, below −20° C., has the drawback that battery warm-up (heating) takes considerable time. In principle, this drawback could be eliminated by increasing heater energy consumption. However, if heater energy consumption were increased, heater temperature would become abnormally high, the board attached to the heater and parts in the vicinity would be over-heated, and heat damage such as deformation could result. As a practical matter, heater energy consumption cannot be increased. Further, in the case where current flow for the heater is from the driving battery, the electrical characteristics of that battery are significantly degraded due to the low temperature. Considering degradation of battery discharge characteristics when current is supplied to the heater, a reduction in heater energy consumption is needed. The heater can also be electrically powered via commercial power by connecting a power cord to a commercial power outlet, and not depending on the driving battery as a power source. However, in this method, warm-up (heating) is troublesome because a power cord must be connected to an electrical outlet. Further, even in this method, warm-up (heating) must be performed while preventing over-heating of the heater, and considerable time is required before battery temperature reaches a set temperature. Finally, since heat capacity of the battery is considerable, large amounts of heat energy are required to warm-up (heat) the entire battery, and this also contributes to long battery warm-up (heating) time.
The present invention was developed with the object of resolving these types of prior art drawbacks. Thus it is a primary object of the present invention to provide a car power source apparatus which can immediately start the car in a location of extreme cold when the ignition key is turned on, without having to warm-up (increase the temperature of) the battery. It is a further object to provide a car power source apparatus which requires no troublesome operations, such as connecting a power cord to an electrical outlet to warm-up (heat) the battery, and which can start the car in an extremely convenient manner.